Cb919 Hornet Slip-ons-rough idle after

**HornetBoy** · 20th December 2007, 09:36

Okay so i just replaced the stock pipes on the 04 900 hornet with G.P.R ones.

and they look awsome,after d got them on i started the bike to check what they sound like ,they sounded great (nice and deep) BUT the idle is very rough (which stock its very clean and stable) by rough i mean it isnt stable and the rev's are all over the place which is noteabley different to stock pipes.

so id like to know does this mean i need to get a Power ommander ? will it cause damage not getting one ?

**skelstar** · 20th December 2007, 09:56

Not sure but I would recommend reading the forums/message board over at www.hondahornet.co.uk

**vifferman** · 20th December 2007, 09:57

Firstly, are you sure you don't have an air leak somewhere, or haven't inadvertantly dislodged a hose or wire somewhere?
Secondly, does your bike still have the O2 sensor(s) connected? If so, then the ECU may still be using the last set of data it got from these - it doesn't actually measure the EGO all the time. Try removing the battery terminals for a minute - this forces the ECU to re-read the sensors used for the fuel injection in 'closed loop' mode, so it should pick up any change in fueling caused by the new zorsts.

I don't think you'll need to get a PC for the bike. I've got a non-standard airfilter and muffler, and apart from a wee bit of hesitation at <3000 rpm, the bike actually runs OK without the PC connected. In fact, the map I'm running has only a bit of tweaking at 5% throttle and low revs, and extra gas to allow for some ignition advance at full throttle and high-ish revs.

Apart from some silly stuff done at the revs that emissions testing is performed at (typically somewhere in the 4 to 6k rpm range), where the bike is set to be very lean and somewhat stifled so it's a bit quieter, and any ultra-silly leanness in the closed-loop mode, the fueling is generally set to be a bit rich throughout the range. This is to allow for individual differences between bikes, and to cater for owners changing zorst and airfilters. Mr Honda doesn't want to get grief from people whose bikes have blown up because they were already running lean and a change of airfilter and zorst made them dangerously lean.

**NordieBoy** · 20th December 2007, 10:19

Sounds like it's running too lean.
Are all the sensors still hooked up?

**HornetBoy** · 20th December 2007, 17:08

Originally Posted by vifferman

Firstly, are you sure you don't have an air leak somewhere, or haven't inadvertantly dislodged a hose or wire somewhere?
Secondly, does your bike still have the O2 sensor(s) connected? If so, then the ECU may still be using the last set of data it got from these - it doesn't actually measure the EGO all the time. Try removing the battery terminals for a minute - this forces the ECU to re-read the sensors used for the fuel injection in 'closed loop' mode, so it should pick up any change in fueling caused by the new zorsts.

I don't think you'll need to get a PC for the bike. I've got a non-standard airfilter and muffler, and apart from a wee bit of hesitation at <3000 rpm, the bike actually runs OK without the PC connected. In fact, the map I'm running has only a bit of tweaking at 5% throttle and low revs, and extra gas to allow for some ignition advance at full throttle and high-ish revs.

Apart from some silly stuff done at the revs that emissions testing is performed at (typically somewhere in the 4 to 6k rpm range), where the bike is set to be very lean and somewhat stifled so it's a bit quieter, and any ultra-silly leanness in the closed-loop mode, the fueling is generally set to be a bit rich throughout the range. This is to allow for individual differences between bikes, and to cater for owners changing zorst and airfilters. Mr Honda doesn't want to get grief from people whose bikes have blown up because they were already running lean and a change of airfilter and zorst made them dangerously lean.

no leaks etc,yea i would assume the o2 sensor is still going as i havent disconnected it ,when you say to disconnect them from the battery terminal this is done with the bike off ,and just turning the bike back on will reset them ?

thanks for the response to mate explains alot.